1. Field of the Invention
An object of the present invention is a method for the automatic gripping of objects, enabling the preservation of at least one geometrical reference element which is related to it, and a grip to implement said method.
2. Description of the Prior Art
In prior art machines for the winding of half cores of deflectors for cathode ray tubes, it is essential to determine the axis of revolution of these half cores with precision and to preserve its reference during the winding stage, in order to position the coil as precisely as possible with respect to the half core. It is also important not to break the half cores when they are gripped by an automatic manipulation grip which transfers them from a centering device to the winding machine.
For example, there is a known half core centering device, described in the French patent No. 2 559 547, which can be used to determine the axis of the revolution with precision despite the relatively high dimensional variation that cores might have in large batch production.
Moreover, there are also known half core gripping machines such as those used in winding machines of the "TAGA" make. These machines work properly but have drawbacks which make their use hardly practical and costly. For, these known grips have calibrated springs acting on the arms and capable of aging differently. These arms have to be strongly locked to keep them from any sliding motion caused by a pneumatically actuated system, entailing the risk that unbalanced thrust forces might be applied opposite to these arms causing the position of the reference axis to be lost. Furthermore, the gripping surfaces of the arms wear out quite quickly through frictional contact with the cores. Finally, the grip cannot be removed from its support without extensively dismantling it and separating it from the pneumatic system, thus complicating maintenance.